Download Fast Facts about Human Genetics • DNA stands for Deoxy

Fast Facts about Human Genetics
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DNA stands for Deoxy-ribo-Nucleic Acid.
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On February 28, 1953, Francis Crick and James Watson figured out the structure of
deoxyribonucleic acid (DNA). That structure, a 'double helix', can "unzip"
(separate into two long strands) to make copies of itself. This discovery confirmed
suspicions that DNA carried an organism's hereditary information.
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DNA molecules are linked, one after another, like pearls on a very long string.
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DNA molecules are the "software" that direct cellular activity and determine
everything about an organism - from what it looks like to how long it is likely to
live. Genes are pieces of this DNA, and are the fundamental units of heredity.
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The complete human genome consists of approximately 3 billion DNA molecules.
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On average, each chromosome has about 65 million DNA molecules.
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A gene is a stretch of DNA molecules (ranging in length from thousands to tens of
thousands of DNA molecules, in some cases they may be even larger).
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Between genes, along the length of a chromosome, there may be long stretches of
DNA, which have no known function.
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A chromosome contains about 1000 genes.
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Humans have approximately 30,000 different genes spread out over the 46
chromosomes.
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Humans get one complete set of genes from each parent.
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In April 2003, the National Human Genome Research Institute (NHGRI) celebrates
the completion of the human genome sequence and the 50th anniversary of the
description of the DNA double helix.
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The nucleus, or control centre, of a cell, is where the DNA is coiled up into
chromosomes. With the exception of reproductive cells, every cell has 46
chromosomes. Twenty-two pairs of the chromosomes are similar in terms of size,
shape and genetic content. The twenty-third pair determines the sex of the
individual, and is composed of either two x chromosomes (female) or an x and a y
chromosome (male).
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DNA molecules are incredibly long. If all of the DNA from all of your cells was
stretched out into a single thread, it would extend to the moon and back about one
million times!